To study effective anti-chaff jamming methods, this paper investigates the echo characteristics of the vessel and the chaff for missile-borne wideband coherent radars. Firstly, the echo model of the missile-borne wideband coherent LFM pulses radar is built, and the range-Doppler image of the echoes is derived. Based on the measured data, the differences of the echoes between the vessel and the chaff are analyzed. Then in terms of the spread feature and the energy evenness of the range-Doppler image, two features of the radar echoes are proposed to distinguish the vessel and chaff. Finally, statistical distributions of the two features are investigated, and we find that the proposed features can be used for chaff jamming identification and suppression.

We propose a method to obtain nano-scale 3D super-resolution in STED fluorescence microscopy. A double-ring-shaped cylindrical vector vortex beam, with an appropriate vortex angle and a proper truncation parameter of the beam, is used to generate a 3D dark spot as the erase spot. A single-ring-shaped radially polarized beam is used as a pump beam, which can generate a sharper 3D bright spot. The volume of the generated 3D dark spot is small and the uniformity of the light wall surrounding the spot is quite high. Consequently, the 3D super-resolution ability of a STED microscope is improved and nano-scale three-dimensional resolutions are obtained.

The authors recently presented a novel microwave tomography method for creating quantitative images of the electromagnetic properties of the interior of unknown objects [1]. This method is based on a time-domain inverse solver which uses the multi-illumination technique and includes the dispersive and heterogeneous characteristic of the object. The Frequency Dependent Finite Difference Time Domain ((FD)2TD) and Genetic Algorithm (GA) technique were utilized for determining unknown characteristics of the object. In the present paper, the calibration of measured data are described and image reconstruction results for preliminary experiments performed at the University of Manitoba's Microwave Tomography Laboratory and at the Institut Frsenel are presented.

We present a theory to describe the transient and steady state behaviors of the active modes of a photonic crystal with active constituents (active photonic crystal). Using a couple mode model, we showed that the full vectorial Maxwell-Bloch equations describing the physics of light matter interaction in the active photonic crystal can be written as system of integro-differential equations. Using the method of moments and the mean value theorem, we showed that the system of integro-differential equations can be transformed to a set of differential equations in slow time and slow spatial scales. The slow time (spatial) scale refers to a duration (distance) that is much longer than the optical time period (lattice constant of the photonic crystal). In the steady state, the slow scale equations reduce to a nonlinear matrix eigenvalue problem, from which the nonlinear Bloch modes can be obtained by an iterative method. For cases, where the coupling between the modes are negligible, we describe the transient behavior as an onedimensional problem in the spatial coordinate, and the steady behaviors are expressed using simple analytical expressions.

Stacked concentric circular antenna arrays (SCCAA's) supporting both the scanning mode and the tracking mode are optimized in both the azimuth and elevation planes. The gbest-guided artificial bee colony algorithm (GABCA) is adopted to optimize the dual-mode field patterns of thinned SCCAA's. Performance comparison of the GABCA with conventional ABCA and particle swarm optimization (PSO) algorithms is also presented.

In this document, a simple and efficacious method to estimate the shielding effectiveness of an electrically large enclosure (SEe) made with pierced metallic plate is shown under uniform and isotropic field conditions, which are produced in a reverberation chamber (RC) where the field is well stirred. The estimate is made by the calculation of the transmission cross sections (TCSs) of the walls of an enclosure and absorption cross sections (ACSs) of the inner losses. TCSs and ACSs are connected to the shielding effectiveness (SE) of the walls and inner losses, respectively; the latter are also connected to the reflectivity of the enclosure internal walls. The comparison with measurements made in an RC matches enough. It shows that the method shown here is sound. Moreover, the results support a recent model that connects SEe to SE by the reflectivity of the enclosure internal walls, and show still further that unloaded electrically large enclosures with distributed apertures are not very efficacious.

Planar antenna array design is one of the most important electromagnetic optimization problems of current interest. This paper introduces a recently developed metaheuristic algorithm, known as the Invasive Weed Optimization(IWO), to the pattern synthesis of planar antenna arrays with desired pattern nulls and sidelobe level by amplitude-only and position-only optimization. The steps in the problem formulation are presented along with a design example that illustrates the performance of the IWO algorithm. Three examples have been presented and solved. Simulation results are proposed to compare with published ones to verify the effectiveness of the IWO algorithm for planar arrays.

Metamaterial based electromagnetic wave absorbers provide perfect absorption only over a narrow bandwidth. In this paper, broadband response is achieved through embedding of one resonator inside another in each unit cell of the metamaterial absorber lattice. These two resonators are oriented in the same direction to achieve reduced coupling between them realizing two absorption frequencies close to each other in order to broaden the effective bandwidth. Paper presents such an absorber at 77 GHz with a bandwidth of 8 GHz with the peak absorption of greater than 98%. The absorber is fabricated on 125 μm thin and flexible polyimide substrate by patterning gold thin film in the shape of two split ring resonators as the metamaterial unit cell. The bandwidth is enhanced by more than a factor of two compared to what could be achieved from a metamaterial with single resonator structure.

Recent progress in the simulation of Casimir forces between various objects has allowed traditional computational electromagnetic solvers to be used to find Casimir forces in arbitrary three-dimensional objects. The underlying theory to these approaches requires knowledge and manipulation of quantum field theory and statistical physics. We present a calculation of the Casimir force using the method of moments via the argument principle. This simplified derivation allows greater freedom in the moment matrix where the argument principle can be used to calculate Casimir forces for arbitrary geometries and materials with the use of various computational electromagnetic techniques.

In this article, a novel simplified dual-composite right/left-handed transmission line (S-DCRLH-TL) is proposed according to the theory of dual-composite right/left-handed transmission line. The electromagnetic characteristics of S-D-CRLH-TL are analyzed by simulator, and the results indicate that the proposed structure has two narrow stopbands; they can be controlled by changing the geometry parameters of the structure. Then, a bandpass filter with dual notched bands is designed by using the unit cell of S-D-CRLH-TL, and the designed filter is simulated, fabricated and measured, the measured and simulated results are in good agreement with each other, showing that the two notched bands centered at 3.60 GHz and 5.50 GHz, and the bandwidths are 9.7% and 7.3%. This designed filter can avoid the interference to UWB communication system effectively, which comes from the signals of WiMAX and WLAN. Besides, in comparison with the other bandpass filter with notched bands, the designed filter has good electromagnetic performances.

In this paper, the comparison of the performances of planar broadband dipole antenna, broadband folded dipole antenna and broadband bent dipole antenna in broadband scenario is presented. All the three antennas have been designed, developed and evaluated for their electrical characteristics such as VSWR, radiation patterns and gain in the frequency range of 100-1000 MHz. Simulated and measured results are presented.

An underground coal mine medium frequency (MF) communication system generally couples its electromagnetic signals to a long conductor in a tunnel, which acts as a transmission line, and exchanges signals with transceivers along the line. The propagation characteristics of the transmission line, which is usually the longest signal path for an MF communication system, play a major role in determining the system performance. To measure the MF propagation characteristics of transmission lines in coal mine tunnels, a method was developed based on a basic transmission line model. The method will be presented in this paper along with the propagation measurements on a transmission line system in a coal mine using the method. The measurements confirmed a low MF signal power loss rate, and showed the influence of the electrical properties of surrounding coal and rock on the MF propagation characteristics of the line.

The six-port architecture reemerges from the search of low-cost, multi-band and multi-standard transceivers. Its inherent advantages, especially its broadband behavior, make this a structure a good candidate to implement a Software Defined Radio (SDR). However, broadband six-port network designs lead to large size circuits, especially for operating frequencies in the lower gigahertz region. New technologies must be explored in order to achieve compact size and low-cost productions for configurable radio terminals and mobile communication applications. In this paper, the Low Temperature Co-fired Ceramic (LTCC) technology is proposed for implementing a broadband six-port receiver. A compact (30 mm × 30 mm × 1.25 mm) four-octave LTCC sixport receiver is presented. Experimental demodulation results show a good performance over the frequency range from 0.3 to 6 GHz. The demodulation of up to 15.625 Msymbol/s signals, i.e., 93.6 Mbps for 64-QAM, has been satisfactorily performed, with a measured Error Vector Magnitude (EVM) value of 3.7%.

In this work we examine several sources of measurement uncertainty that can hinder the use of time-domain microwave techniques for breast imaging. The effects that are investigated include those due to clock and trigger jitter, antenna movements, discrepancies in antenna fabrication, and random measurement noise. We explore the significance of the noise contribution of each effect, and present methods to mitigate them when possible and necessary. We demonstrate that, after applying the aforementioned methods, the noise is minimized to the noise floor of the system, thereby enabling successful tumor detection.

Due to the increasing complexity of metamaterial geometric structures, direct optimisation of these designs using conventional approaches, such as Gradient-based and evolutionary algorithms, are often impractical and limited. This is in part due to the inherently high computational cost associated with running multiple expensive high-fidelity full-wave simulations, commonly required to optimise the constitutive parameters of a single metamaterial particle. In order to alleviate this issue, we propose an efficient optimisation approach which exploits the Co-Kriging methodology, such that we can successfully couple varying levels of discretisation and solver accuracy obtained from a 3d full wave numerical solver suite. In contrast to other optimisation strategies, we investigate the improvement in efficiency of optimisation through the use of the LOLA-Voronoi, in conjunction with Expected Improvement and the embedding of a trustregion framework within our optimisation algorithm, to accelerate the convergence of Co-Kriging. Finally, the effectiveness of the outlined algorithm will be demonstrated by a quantitative evaluation of the performance of optimised planar 2D negative index of refraction structures.

This paper presents a new analytical method for predicting magnetic field distribution and levitation force in three configurations of high temperature superconducting (HTSC) maglev vehicles. The permanent magnet guideways (PMG) are composed with ferromagnetic materials and NdFeB permanent magnets. The proposed analytical model is based on the resolution in each region of Laplace's and Poisson's equations by using the technique of separation of variables. For the study, we consider the HTSC as a perfect diamagnetic material. The boundary conditions and Fourier series expansion of interfaces conditions between each region are used to find the solution of magnetic field. The developed analytical method is extended to compute the magnetic field distribution generated by the three types of PMGs when removing the HTSC bulk. Magnetic field distribution and vertical force obtained analytically are compared with those issued from the finite element method (FEM).

Traditional contacting measurement has numerous disadvantages, including high cost, high damage rate, low mobility, etc. In this study, to resolve these serious problems, a simiple, broadband non-contacting loop has been disigned to transmit and receive a signal. An equivalent dual-port non-contacting measurement model and a theorem of vertical coupling capacitance and inductance have been proposed. From the results of the dual-port model simulation and the fabricated sample measurement, a theorem of singal reconstruction and novel non-contacting measurement presented.

In this paper, a 4 × 4 indoor Multiple-Input Multiple-Output Ultra-Wideband (MIMO-UWB) measurement campaign in the 2-5 GHz bandwidth is presented. The main contribution of this work is the impact of radio-wave polarization as well as the effect of frequency dependence on the capacity of MIMO-UWB systems working in an office environment. To accomplish this, the capacityfor different polarizations is analyzed under two different assumptions: constant or variable Signalto-Noise Ratio.

A compact stacked bidirectional antenna is presented for dual-polarized 2.4 GHz WLAN applications in this paper. The antenna consists of an orthogonal coupling feed driver and stacked director array, with the overall size 50×50×160 mm³. Dual-polarization is excited by the orthogonal coupling line, and the director array contributes to the bidirectional radiation pattern. Both the coupling feed driver and directors are printed on FR4 substrate and supported by plastic pillars. The measured bandwidth of the two ports are 2.33-2.62 GHz (11.8%) and 2.32-2.64 GHz (13%) under the condition of VSWR less than 2. The isolation between two ports are lower than -20 dB. The peak gains along one radiation direction are 9.65 dBi and 9.30 dBi for each port, with highly symmetric bidirectional beam pattern. The proposed antenna is compact and stable, and suitable for bidirectional 2.4 GHz WLAN applications.

In this paper, ultra-wideband characteristics of a hexagonal wide slot antenna with dual band-notched property have been proposed and experimentally investigated. By etching a pair of L-shaped slots and embedding a pair of parallel strip conductors, dual band-notched properties in WiMAX/C-Band satellite application and WLAN band are achieved respectively. Good impedance matching is obtained over a wide band by designing the feed structure with a 50 Ω microstripline loaded by a tuning stub. The stub is proposed to have one hexagonal section and one straight section. The proposed antenna operates over 2.0 GHz-10.7 GHz range, for VSWR≤2,excluding the two rejection bands from 3.4 GHz to 4.3 GHz and 5.12 GHz to 6.4 GHz having rejection level VSWR of 7.84 and 6.5 respectively. The impedance bandwidth of the antenna is 5.35:1. The proposed ultra-wideband structure also exhibits constant group delay, satisfactory gain and high radiation efficiency in the pass band.